rebuilt water pump runs hot

Is there play in the pump shaft? If there is, your impeller could be too far behind the water outlet and not pumping properly. I think I have this problem with my car, after I installed a new pump, it has been overheating. Timing and fuel could be a problem, too.
 
If the new shaft has a impeller that hasn't been ground down, and you have an after market radiator , you will have to take 1/3 of the blades. Plus check everything else that everyone is saying. and a 160 thermostat will help.
 
oldwoodsman said:
somewhere here I read that people increase the size of the bypass in the thermostat. Is that correct?
Click to expand...
No need to do that, they usually have a tiny vent hole in the valve & also, the valve is NOT a perfect seal. When Minerva was COLD, I revved her up, & was surprised:eek: at how much water was flowing into the top tank. "MAYBE" the pump pressure pushes the valve open, slightly:confused:------Bill W.
 
ran some test today
1. Put the old fan on the new shaft and impeller ran up the "hill" at 40 mph engine temp 184*
2. New fan on the new shaft and impeller up the "hill" same speed same spark advance and gav setting engine temp 199*
3. added water wetter same hill, speed, and settings engine temp 194*
the only difference I can see is the pulley on the new fan is narrower and the belt rides higher on it, then it does on the old pulley hence the fan and water pump turn at a slower speed.
the ambient temp was 83* for all three runs.
The belt width is .630 does anybody think a narrower belt might make a difference?
What should the belt width be?
Thanks Tim
 
oldwoodsman said:
ran some test today
1. Put the old fan on the new shaft and impeller ran up the "hill" at 40 mph engine temp 184*
2. New fan on the new shaft and impeller up the "hill" same speed same spark advance and gav setting engine temp 199*
3. added water wetter same hill, speed, and settings engine temp 194*
the only difference I can see is the pulley on the new fan is narrower and the belt rides higher on it, then it does on the old pulley hence the fan and water pump turn at a slower speed.
the ambient temp was 83* for all three runs.
The belt width is .630 does anybody think a narrower belt might make a difference?
What should the belt width be?
Thanks Tim
Click to expand...
anybody on belt width?
 
Went on a 900 mile trip this last week. The first day out had it overheat on two long hill climbs, so I put the old pulley and fan on, had many hard climbs after that with no overheating problems. It appears to me the pulley groove width is narrower on the aluminum pulley thus turning the water pump slower causing the over heating. The pulley & fan change made a 20* difference in engine temp.
 
Bill and Brobrian, I have heard the theory about water circulating too fast to get rid of the heat because it is not in the radiator long enough. I'm doubtful about that and would like to hear the opinion of others.
Here's why I'm doubtful.
If the water is circulating fast enough to spend too short a short time in the radiator to cool, then it is circulating fast enough that it is circulating through the block for too short a time to get hot. Put another way, the temperature of the engine is stable only when the heat being dissipated by the radiator matches the heat produced by the motor. Within limits, I suspect that water speed doesn't matter.
I'd like to see one of those infrared thermometers used to check the temp at top and bottom of the radiator on a car with fast moving water and again with it circulating at a lower speed.
 
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